Functional Programming - Combine an Array into a String Using the join Method

[Qlander]

THE TASK Use the join method (among others) inside the sentensify function to make a sentence from the words in the string str. The function should return a string.

I dont understand my code isnt working here. Ive checked the solution listed in the hints and I feel that this code is functionally the same…

function sentensify(str) {
  // Only change code below this line
let newArr = str.split(/\W/);
newArr.join(" ");
return newArr;

  // Only change code above this line
}

sentensify("May-the-force-be-with-you");

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Challenge: Functional Programming - Combine an Array into a String Using the join Method

Link to the challenge:

freeCodeCamp.org

[Salathor]

@Qlander

function sentensify(str) {
  // Only change code below this line
let newArr = str.split(/\W/);
newArr.join(" ");
return newArr;

  // Only change code above this line
}

sentensify("May-the-force-be-with-you");

Take a look at the .join() function. Check whether it modifies the array in place or returns something new!

[Qlander]

The .join() function does not modify the array here. If I remove the join function then I still get the same output.

[Qlander]

Why does return str.split(/\W/).join(" ");

return a different output than let newArr = str.split(/\W/); newArr.join(" "); return newArr; ?

[Salathor]

Yes, I know! I’m not suggesting you remove .join(), I’m suggesting a careful reading of how it operates on arrays and figuring out how to access what it does for you (without trying to give away the answer).

Just takes a while to remember which ones affect return values vs manipulate-in-place.

[Qlander]

I figured out that it worked when I assigned it to a new variable and then returned that new variable. But Im still finding this rather confusing. Guess now I know moving forward.

[Salathor]

Yup, it’s just one of those weird things you have to remember (or remember to look up in the docs regularly). Some functions modify the array in place, and some just return a copy. I have yet to figure out why some do one or some do the other, so I just always test it or look it up if it isn’t one I’m sure of.